Separation by implantation of oxygen (SIMOX) is a technique used in the semiconductor industry in fabricating SOI substrates that can be used in the manufacturing of ICs. SIMOX typically involves using high-energy ions to implant a large dose of oxygen ions beneath the surface of a bulk Si-containing wafer. Upon high-temperature annealing, the implanted oxygen ions form a continuous BOX region which electrically isolates the Si at the surface (i.e., superficial Si layer). Typically, prior art SIMOX processes have been used to fabricate SOIs with a superficial Si layer and a BOX thickness of several thousand angstroms.
In some applications, it is desirable to form discrete and isolated BOX regions within a Si-containing substrate while not forming a BOX region in other portions of the Si-containing substrate. Hence, there is a growing need for providing such patterned SOI regions. Patterned SOT regions formed within a Si-containing substrate are especially needed for future high performance Si-containing ICs, optical communication devices and three-dimensional device and circuit integration.
Despite this need, there are many challenges in fabricating patterned SOI regions within a Si or SOI-containing substrate. For example, the following criteria needs to be met:
(i) maintaining a smooth surface topology between the patterned and unpatterned regions;
(ii) controlling and eliminating crystallographic defects at the edge of the mask used during ion implantation to create patterned regions; and
(iii) controlling and eliminating crystal defects between the nearby oxide islands.
The inventors are not aware of any prior art method which meets the above-mentioned criteria. Hence, there is a need for providing a method which is capable of forming at least one patterned SOI region within a Si-containing or SOI-containing substrate which meets the above-mentioned criteria.